I have seen this first hand recently one of my females layed a whole clutch of small not so nice looking eggs, I incubated just to give them a chance and they started showing blue-green spots within the first week some before others. What i found strange was that there was no rotten egg odor, when i cut them open eventually their was a thicker crusty yolk around the shell and the inner was still liquid, it still look and smelled very much like regular egg yolk.